Studies on Microscopic Observations of Tissue Structures and Dietary Fiber Components in Persimmon (Diospyros Kaki) Leaves

Abstract

Morphological and histochemical changes of tissue structures in persimmon leaves were investigated using a fresh leaf, a freeze - dried powder and a semi-purified dietary fiber preparation isolated from the powder. Concentration and composition of dietary fiber (DF) and other chemical components in the latter two samples were also analyzed. Morphological observation showed that the fresh persimmon leaf distributed palisade and spongy parenchyma between the upper and lower epidermis. It was observed by histochemical techniques that the cell walls and vacuoles of the cells were stained strongly by Periodic Acid Schiff (PAS) reagent. The PAS reaction with the cell walls and vacuoles of May and July leaves was much stronger than those of the September leaf. The cell walls of all fresh leaves each month were stained by Alcian Blue (AB, pH2.5 or pH1.0) with almost the same intensity. The cells in the freeze-dried specimen were found to be morphologically nearly intact and the cell walls were stained by PAS and AB reagents with the same intensity as those of fresh leaves. The existence of polysaccharides, which were stained by PAS and AB reagents, was also observed in the semi-purified DF preparation. The freeze-dried specimen contained from 41 to 43% (dry basis) DF which consisted of almost equal amounts of lignin, cellulose and hemicellulose. These results suggest that persimmon leaves are constituted by 4 main tissues and contain dietary fiber with a complex structure consisting of nearly an equal amount of major plant fiber components and a small amount of pectic substance and mucopolysaccharide-like substances as acid polysaccharides in the cell walls.